US1603701A - Refining of petroleum oils and distillates - Google Patents

Description

Patented Oct. 19, 1926.

UNITED STATES I 1,503,761 PATENT OFFICE.

PAUL MCMICHAEL, OF'ELUSHING, NEW YORK, ASSIGNOR TO HYDROCARBON REFIN- ING PROCESS COMPANY INC., 01? NEW YORK, N. Y., A CORPORATION OF NEW YORK.

REFININGOF PETROLEUM OILS AND DISTILLA'I ES.

No Drawing.

This invention relates to an improved method for refining petroleum hydrocar' bone, and ,more particularly relates to a method for refining light petroleum oils and distillates, especially gasoline-containing cracked oils and pressure distillates.

Light petroleum distillates, particularly those intended for use in automobile interm and resin.

standing, and the instability of certain oils to prolonged exposure to light, are largely due to the presence in the oil of unsaturated material such asterpenes, diolefines, and

isomers, polymers and homologues or deriv-' atives thereof. All unsaturated compounds, however, arenot ob ectionable in these respects, and some unsaturated compounds,

such as the olefines, constitute an excellentv and advantageous constituent for motor fuel, and their removal constitutes an unnecessary loss. I gum forming compounds are partlcularly objectionable 1n OllS 1ntended for use in internal combustion engines because they tend to form gum-my deposits in various parts of the engine and to form corroslve combustion products.

Hitherto, the general practice in there-f fining of such oils has involved initial treatsulphuric acid'for removing them. Treat-' ment with strong sulphuric acid substantially denudes the oil of any olefines and similar unsaturated compounds it may have contained prior to the treatment and tends to introduce sulphur into the oil in the form of alkyl sulphates. Refining methods have also been proposed 'involvinginitial treatment of the oil with quite dilutesulphuric acid, but such methods, if carried out in a manner to avoid destruction or removal of the olefine-s and similar compounds, do not produce a stable product of-good color and odor and free from gum and resin forming bodies. Another disadvantage of those previous methods of, refining with sulphuric Sulphur compounds and Application filed January 11, 1924. Serial No. 685,703.

acid which have been found commercially useful has been the number of distillations involved.

According to the present invention, the oil to be refined is subjected to an initial treatment with anaqueoussolution of an alkali or an alkali earth at ordinarytemperatures. Following the;alkalinetreatment,the oil is subjected to a regulated treatment with relatively dilute sulphuric acid. After the acidtreatment, the oil is subjected to a further alkaline treatment at ordinary temperature,

'or toa distillation in the presence of an alkali or an alkali earth or a solution thereof, .or toa combination of these two latter treatments. The 'oil may be washed followifig the initial alkaline treatment and the acid treatment, and" treatment with a com.- minuted solid decolorizing. agent may be. employed following the final alkaline treatment.

The initial alkaline treatment removes some sulphur compounds and apparently as sists in the subsequent removal of other sulphur compounds by modifying. them to a less refractory form and also appears to assist in the removal of gum forming material. When first subjected to treatment with an alkali, diflicultly removable objectionable compounds necessitating the use of strong acid are not introduced into the oil and. components tending to form such objection able compounds upon treatment with sulphuric acid are largely eliminated. In conjunction with the preliminary alkaline'treatment, the rigor of the subsequent sulphuric acid treatment can be reduced sufliciently to prevent formation of oil-soluble alkyl sul phates and to substantially avoid removal of olefines and similar edesirable unsaturated compounds, while, at the same time, sulphur compounds and gumforming compounds can be substantially completely removed or converted-to a form readily removed with a light alkaline treatment or simple steam distillation. The chemical treatments are carried out at ordinary temperature, reducing evaporation losses, and the small number of operations reduces mechanical losses. A single distillation is usually suflicient, if any distillation is required, to produce a completely refined oil. The refined product of the invention is of good colorand odor, substantially free from sulphur compounds and gum and resin foima product of the invention somewhat suggests ing 'compounds, and retains practically all of the olefines and similar desirable unsaturated compounds. The odor of the refined the presence of monohydric alcohols.

Advantageously, the initial alkaline treatment is effected with a strongly caustic solution, for example, with a solution of caustic soda corresponding to a concentration having a specific gravity equal to about 38 to 40 B.

The oil and the alkaline solution are thor-' oughly mixed and agitated together. Intermittent agitation, for example, may'be em ployed over a period of from 1 to 4 hours, depending upon the concentration of the al kaline solution and the composition of the distillate under treatment. After this treatment, the oil and the alkaline solution may be separated by permitting the mixture to stand and withdrawing either the alkaline solution or the oil, and the separated oil thoroughly washed with water to remove any excess caustic. The oil and wash water 'may' be separated by settling.

Sulphuric acid of a concentration between about and 83% will remove diolefines,

terpenes and similar gum forming com-.

pounds, or will convertthem to a form capable 'of removal by subsequent alkaline treatment, but acts very slowly, if at all,

upon unsaturated compounds such as the olefines. Following the initial alkaline treatment, the oil is agitated with such relatively dilute sulfuric acid over a period suflicient to "remove the gum and resin for-mingconstituents without effecting material loss-due to destruction or removal of unobje'c'tionable unsaturated compounds. The total amount of sulfuric acid employed and the total time .of agitation of the oil with the sulfuric acid depends upon the degree of concentration of the acid employed and the composition of the oil being treated. Advantageously,'the total quantity of acid may be divided into several portions and the oil treated successively with these several portions. Using from 1.5% to 15% of the weight of the oil of sulphuric acid of a specific gravity of 60 B, the total time of agitation may aggregate from 1 to 4 hours. Following separation of the oil and acid after acid treatment,

the oil may be washed with water to removewith a solution of an alkali or an alkali earth for a period for example, of from 30 minutes to 1 hour, theminture allowed to settle to effect separation of the oil and alkaline solution, and the solution or oil drawn off. In some cases, even though the final alkaline treatment at ordinary temperature is not suflicient, such lower boiling oils can be completely refined with the production of a satisfactory product without distillation by subjecting the oil after this alkaline treatment to treatment with a comminuted solid decoloriaing agent, such as infusorial earth, activated carbon, silica. gel,

boneblack or fullers earth. The oil may be filtered through the decolorizing'agent or a small amount of the decolorizing agent may be agitated with the oil and subsequently separated by filtration.

- Where distillation is necessary to com ,plete the refining, the procedure is determined in part by the boiling range of the original fraction submitted to treatment and the desired boiling range ofthe completely refined product. Assuming that 225 C. is approximately the end boiling point desired in the final product, if the major portion of the oil distills below about 225 0., for e ample more than about the entire fraction is advantageously submitted to distillation in the presence of a fixed alkali, that I is of an alkali or an alkali earth, and the fraction constituting the desired final product separately collected Distillation may he continued and the remaining oil collected as a separate fraction. This secondary prod not is frequently discolored, shading from a light yellow to a brown, but it is substanseparate a fraction "having the desired boilr ing range prior to the refining operation. This method of procedure eliminates unnecessary consumption of caustic and acid in treating that part of.tlie oil which is not within the boiling range of the desired final product. The additional initial distillation is preferable if it is more economical than the additional amount of acid and caustic required to treat the entire fraction. The boiling range of the oil being treated, before or at any time during treatment, can be. readily determined by the fractional distillation of a small'sample.

Any saponifiable compounds contained in theoriginal oil are removed in the form of soap by the initial alkaline treatment whereas they are usually decomposed if subjected to initial acidtreatment. These compounds canbe recovered by acidulation of the soap formed by the initial alkaline treatment; Terpenes, diolefinesand other gum and resin formingbodies removed with the sulphuric acid; can, to a large extent, be recovered from the acid sludge by dilution of thisf sludge with water.

The following specific example will serveto'further illustrate the inventiomaltl oughit will-be understood that the invention 1s not in any way limited thereby. A pressure distillate having an iodine absorption number of 26.6, a sulfur content of 0.152% by weight, and a gum content of 0.4212 grams per hundred c. c. measured at 15 (3., was

agitated for approximately one hour at ordinary temperature (about 15 C.) with 2.5%

by .volume of a 40 B.-water solution of sodium hydroxide and after separation of the oil and alkali by settling was washed with approximately 5% by volume of water after the last acid treatment the oil was' washed with approximately 5% by volumeof water to remove excess acid. The loss duringthis step was about 1.5% by volume on the original distillate treated. The par-i tiallyrefined oil thenhad an iodine absorption number of 24.9, a sulphur content of 0.012% by weight, and a gum content of 0.023 grams per hundred c. 0. measured at 15 C. The separated oil was then dis tilled with steam in the presence of'about an equal volume of a saturated water solu tion of hydrate of lime. The distillate was collected in two fractions, the first amount ing to about 82.7% by volume of the original distillate and the second to about 14.6%. The first fraction constituted a completely refined product, was water white, had a distinctly agreeable odor, an iodine absorption sulphur, and had a gum content elf-0.0008

grams per hundred c. 0. measured at 15 C.

It will thus be seen that the present invention provides an improved method of refining hydrocarbon oils and distillates which involves a minimum of evaporation and mechanical losses during chemical treatment and which also eliminaiesunnecessary distillation. It will also be seen thatthis invention eliminates unnecessary loss due to the destruction or removal of desirable unsaturated compounds such as olefines during the refining operation and permits retention in the refined product of substan-v tially all of the olefines and similar unsaturated constituents boiling within the range of'the refined productthat were contained in the original oil treated.

I claim:

1. A process-of refining petroleum oils and distillates boiling substantially completely below about 225 (1, which com prises agitating the oil with a solution of an alkali, thereafter subjecting the oil to treatment with from'about 1.5% to 15% of sulphuric acid of a concentration betweenabout 7 0% and 83% H SOJ and subsequently-steam distilling the separatedoil in the presence of a fixed alkali;

2. A process of refining petroleum oils and distillates boiling substantially completely below about 225 0., which comprises agitating the oil with a solution of an alkali.

thereafter subjecting-the oil to treatment with from about-1.5% to 15% of sulphuric acid of a concentrationbetween about 70% and 83% H SO thereafter steam, distilling theseparatedoil'in the presence of a fixed. Y

alkali and subsequently treating the oil with a comminuted solid decolorizing agent.

- 3.1 1 method of refining petroleum oils and distill-ates, which comprises agitating the oil with a solution of an alkali, separating the oil from the alkaline solution and agitating the separated oil with dilute sulphuric acid, separating the oil from the acid 4 sludge and steam distilling the separated oil. in the presence of a fixed alkali, and separately collecting the traction ofthe desired boiling range.

4. A method of refining petroleum oils and distillates, which comprises subjecting ice the oil to treatment with a. solution of an alkali, separating the oil from the alkalinesolution and treating the separated oil with sulphuric acid of a concentration between about 7 0% and 83% H 80 separating the oil from the acid sludge and distilling the separated oil with steam in the presence of a fixed alkali and, separately collecting the fraction of the desired boilingrange. number of 25.5, contained only a trace of